Headrig slabbing heads are used extensively throughout the world. The conventional practice is to mount a log to be sawn on a reciprocating carriage and feed the log past a headrig slabbing head which cuts a face on the log prior to the log being fed past the band saw of a headrig bandmill. The bandmill makes a second cut parallel to the newly cut face to create a board in one pass of the reciprocating carriage. Significant time savings result by making two cuts in one pass. As well, the slabbing head produces good quality wood chips that ca be used in paper making.
With existing headrig slabbing units, a slabbing head has to be sized to cut the largest diameter log. A slabbing head has an optimum chipping height with respect to the log to produce correctly sized chips and a uniform cut face. A very large slabbing head cutting on a small log will be operating outside this optimum chip height and will therefore produce poor quality chips and a poor quality surface. Typically, when processing a batch of logs, the average log diameter is about one third the diameter of the largest log, therefore a very large slabbing head is usually working on logs of less than optimum diameter. Additionally, large slabbing heads are obviously more expensive than smaller ones as they have more knives which require more maintenance.